<template>
  <div class="slider" ref="slider">
    <div class="slider-group" ref="sliderGroup">
      <slot> </slot>
    </div>
    <!-- <div class="dots">
      <span
        class="dot"
        :class="{ active: currentPageIndex === index }"
        v-for="(item, index) in dots"
        :key="index"
      ></span>
    </div> -->
  </div>
</template>

<script type="text/ecmascript-6">
import { addClass } from 'assets/js/dom.js'
import BScroll from 'better-scroll'


export default {
  name: 'slider',
  props: {
    loop: {
      type: Boolean,
      default: true
    },
    autoPlay: {
      type: Boolean,
      default: true
    },
    interval: {
      type: Number,
      default: 4000
    }
  },
  data() {
    return {
      dots: [],
      currentPageIndex: 0
    }
  },
  mounted() {
    setTimeout(() => {
      this._setSliderWidth()
      // this._initDots()
      this._initSlider()

      if (this.autoPlay) {
        this._play()
      }
    }, 20)

    window.addEventListener('resize', () => {
      if (!this.slider || !this.slider.enabled) {
        return
      }
      clearTimeout(this.resizeTimer)
      this.resizeTimer = setTimeout(() => {
        if (this.slider.isInTransition) {
          this._onScrollEnd()
        } else {
          if (this.autoPlay) {
            this._play()
          }
        }
        this.refresh()
      }, 60)
    })
  },
  // activated() {
  //   this.slider.enable()
  //   let pageIndex = this.slider.getCurrentPage().pageX
  //   this.slider.goToPage(pageIndex, 0, 0)
  //   this.currentPageIndex = pageIndex
  //   if (this.autoPlay) {
  //     this._play()
  //   }
  // },
  // deactivated() {
  //   this.slider.disable()
  //   clearTimeout(this.timer)
  // },
  // beforeDestroy() {
  //   this.slider.disable()
  //   clearTimeout(this.timer)
  // },
  methods: {
    refresh() {
      if (this.slider) {
        this._setSliderWidth(true)
        this.slider.refresh()
      }
    },

    _setSliderWidth(isResize) {
      this.children = this.$refs.sliderGroup.children

      let sliderWidth = this.$refs.slider.clientWidth

      this.children.forEach(child => {
        addClass(child, 'slider-item')
        child.style.width = sliderWidth + 'px'
      })

    },

    _initSlider() {
      this.slider = new BScroll(this.$refs.slider, {
        scrollX: true,
        scrollY: false,
        momentum: false,

        slide: {
          loop: this.loop,
          threshold: 0.3,
          speed: 400
        }
      })

      this.slider.on('scrollEnd', this._onScrollEnd)

      this.slider.on('touchEnd', () => {
        if (this.autoPlay) {
          this._play()
        }
      })

      this.slider.on('beforeScrollStart', () => {
        if (this.autoPlay) {
          clearTimeout(this.timer)
        }
      })
    },
    _onScrollEnd() {
      let pageIndex = this.slider.getCurrentPage().pageX
      this.currentPageIndex = pageIndex
      if (this.autoPlay) {
        this._play()
      }
    },
    _initDots() {
      this.dots = new Array(this.children.length)
    },
    _play() {

      clearTimeout(this.timer)
      this.timer = setTimeout(() => {
        console.log("next");
        this.slider.next()
      }, this.interval)
    }
  }
}
</script>

<style scoped lang="stylus" rel="stylesheet/stylus">
@import '~assets/stylus/variable';

.slider {
  width: 100%;
  min-height: 1px;

  .slider-group {
    position: relative;
    display: inline-block;
    white-space: nowrap;

    .slider-item {
      display: inline-block;
      box-sizing: border-box;
      overflow: hidden;
      text-align: center;

      a {
        z-index: 10;
        display: block;
        width: 100%;
        overflow: hidden;
        text-decoration: none;
      }

      img {
        display: block;
        width: 100%;
      }
    }
  }

  .dots {
    position: absolute;
    right: 0;
    left: 0;
    bottom: 12px;
    transform: translateZ(1px);
    text-align: center;
    font-size: 0;

    .dot {
      display: inline-block;
      margin: 0 4px;
      width: 8px;
      height: 8px;
      border-radius: 50%;
      background: $color-text-l;

      &.active {
        width: 20px;
        border-radius: 5px;
        background: $color-text-ll;
      }
    }
  }
}
</style>